【作者】 何涛；

【导师】 郑有良； 江千涛； 蒲宗君；

【作者基本信息】 四川农业大学 ， 作物， 2015， 硕士

【摘要】 本研究对栽培二粒小麦、沙融山羊草及二者远缘杂交双二倍体后代的低分子量谷蛋白亚基(Low molecular weight glutenin subunit,LMW-GS)基因进行分离,以探寻LMW-GS基因远缘杂交过程中的遗传变异情况,探讨其变异规律,为品质育种实验提供基础。主要研究结果如下：1、利用已知的LMW-GS基因设计不同类型特异引物,共获得64条基因。其中,LMW-m共分离得到33条基因,沙融山羊草分离得到9条真基因和1条假基因,基因相似性为68.20%-99.70%；栽培二粒小麦分离得到6条真基因和6条假基因,基因相似性为53.11%-99.89%：双二倍体分离得到5条真基因和6条假基因,基因相似性为90.25%-99.89%；双二倍体与沙融山羊草基因相似性为63.74%-74.98%,与栽培二粒小麦基因相似性为55.90%-99.89%。LMW-s共分离出31条基因,沙融山羊草分离得到10条真基因和1条假基因,基因相似性为86.24%-99.79%；栽培二粒小麦分离得到9条真基因和1条假基因,基因相似性为49.12%-98.56%；双二倍体分离得到10条真基因,未分离出假基因,基因相似性在62.95%-99.81%；双二倍体与沙融山羊草基因相似性为62.95%-99.81%,与栽培二粒小麦基因相似性为48.03%-99.80%。2、将双二倍体与亲本进行相似性比较,LMW-m分离得到双二倍体的11条基因,全部与亲本栽培二粒小麦相似型最高。LMW-s分离得到的10条基因中,全部与亲本沙融山羊草相似型最高。3、在栽培二粒小麦、沙融山羊草及二者远缘杂交双二倍体三个材料中,无论是LMW-m还是LMW-s,真基因Ks/Ka值都较大,表明在LMW-m和LMW-s基因中,同义突变频率(Ks)比非同义突变频率(Ka)高；在假基因中,Ks/Ka值较小,非同义突变频率(Ka)比同义突变频率(Ks)高。4、LMW-m和LMW-s蛋白的氨基酸序列的一级结构都主要由4个部分组成,即信号肽、N末端区、重复区和C末端区。信号肽与N末端区是比较保守的,变异很少。而重复区和C末端区变异程度较大。基因间的差异体现在在单个或者多个碱基的缺失、替代和插入。5、针对LMW-m和LMW-s基因进行聚类分析,结果显示,LMW-m基因主要分为4类,其中双二倍体与亲本栽培二粒小麦聚在一起,表明双二倍体分离出的LMW-m主要来源于栽培二粒小麦。而LMW-s则不同,LMW-s主要分为2类,双二倍体与沙融山羊草聚在一起,表明双二倍体分离出的LMW-s主要来源于沙融山羊草。更多还原

【Abstract】 Aiming at revealing genetic variation of genes encoding LMW-GS of Ae. sharonensis, T. dicoccum and their hybrid amphiploid, we conducted isolating and multiple alignment of these genes. These results will be informative for quality improvement at breeding project of bread wheat. The results are as follows:1. Totally,64 gene sequences encoding LMW-GS were identified in this study. Of them,34 belong to type of LMW-m and the other 31 LMW-s. Among the 34 sequences (LMW-m type),9 genes and 1 pseudogene were identified from Ae. sharonensis with similarity ranging from 68.20% to 99.70%; 6 genes and 6 pseudogenes from T. dicoccum with similarity ranging from 53.11% to 99.89%; 5 genes and 6 pseudogenes from hybrid amphiploid with similarity ranging from 90.25% to 99.89%. While among the 31 sequences (LMW-s type),10 genes and 1 pseudogene were identified from Ae. sharonensis with similarity ranging from 86.24% to 99.79%; 9 genes and 1 pseudogenes from T. dicoccum with similarity ranging from 49.12% to 98.56%; 10 genes from hybrid amphiploid with similarity ranging from 62.95% to 99.81%.2. All of the eleven gene sequences encoding LMW-m isolated from hybrid amphiploid have higher similarity with those from the parent of T. dicoccum than those from Ae. sharonensis; while, all the 10 LMW-s genes from hybrid amphiploid have higher similarity with those from the parent of Ae. sharonensis than those from T. dicoccum.3. In the materials with types of LMW-m and LMW-s, the value of Ks/Ka was higher, showing that the synonymous substitutions per site for pairwise comparisons from LMW-m and LMW-s were more than non-synonymous substitutions. On the contrary, the value of Ks/Ka for pseudogenes was lower, showing that non-synonymous substitutions per site for pairwise comparisons from LMW-m and LMW-s were more than synonymous substitutions.4. The structures of amino acid for LMW-m and LMW-s were composed of signal peptide, N terminal, repeats area and C terminal. The domains of signal peptide and N terminal were conserved compared with repeats area and C terminal. The causes contributed to the differences among various genes were insertion, deletion and substitution of a given nucleotide acid.5. Phylogenetic analysis of genes encoding LMW-m and LMW-s showed that genes encoding LMW-m could be divided into 4 groups. The majority of genes from the hybrid amphiploid were classified into the same clade as those from T. dicoccum, showing that they were mainly derived from the parent of T. dicoccum. However, LMW-s genes were mainly divided into 2 groups. Most of the genes from the hybrid amphiploid were classified into the same clade as those from Ae. sharonensis, showing that they were mainly derived from the parent of Ae. sharonensis.更多还原